Investor Carl Icahn - best known for trying to stop Mike Dell from taking Dell the company private - has applied more gentle pressure to Apple boss Tim Cook to get the chief exec to beef up the iPhone maker's share buyback.

During the Nasdaq outage, Icahn tweeted that he'd been chatting to Cook and was planning a dinner with the CEO next month to talk more about the fruity firm's buyback programme:

Spoke to Tim. Planning dinner in September. Tim believes in buyback and is doing one. What will be discussed is magnitude.

Icahn said a week ago that he'd had a "nice conversation" with the Apple chief about how he reckoned that the firm needed to do a larger buyback. The activist investor, along with other fruity shareholders, want a larger piece of Apple's $147bn cash mountain.

At the same time, the billionaire said he'd upped his stake in the iDevice-maker, which sources now say could be worth between $1bn and $1.5bn. The new position, along with comments that Apple's stock was undervalued, helped the firm's shares to rise five per cent on 13 August. But his talk of little chats with Cook failed to budge the stock, which only gained 0.12 per cent after trading resumed following the Nasdaq's downtime.

Back in April, Cupertino said it would return $100bn to shareholders by the end of 2015, raising its dividend by 15 per cent and boosting its share buyback scheme to $60bn, six times more than what had previously been planned.

But some investors, including Icahn, still aren't happy. He told Reuters last week that he reckoned Apple could withstand a $150bn buyback programme if it borrowed some money and doing so would help its shares to jump back to the $700 heights they reached around this time last year. ®